Digital data processing requires multiplication and accumulation of data. For this purpose, digital signal processors (DSP) may include a multiply or a multiply-and-accumulate (MAC) unit, which is adapted to multiply and accumulate operands for various controlling and data processing tasks. As multiplication and accumulation of numbers is one of the basic and central data processing steps of data processing applications, there is a general motivation to improve multiply-and-accumulate units towards faster operation and reduced complexity.